Spring interiors for mattresses, seats and the like

ABSTRACT

In the manufacture of spring interiors for mattresses, seats and the like a plurality of springs are linked together by helical wires which are rotated and advanced much in the manner of screws. In order to prevent the helical wires becoming unlinked stops are formed by distorting the helical wires at positions spaced from their ends. Each stop preferably comprises a closed loop, and this preferably embraces a wire of an adjacent spring.

United States Patent Pearson 1 1 SPRING INTERIORS FOR MA'I'IRESSES, SEATS AND THE LIKE lnventor: George II. Pearson, Corner Gate" High Park Avenue, Wollaston, Stourbridge, Worcestershire, England Assignee: Slumberland Group Limited, Tyseley, Birmingham, England Filed: May 11, 1970 Appl. No.: 36,203

Foreign Application Priority Data May 13, 1969 Great Britain ..24,218/69 US. Cl. ..5/269, 140/3 CA, 140/927,

267/91 lnt. Cl. ..B2lf 27/16, B2lf 33/04 Field of Search 140/3, 3 CA, 89, 92.3, 92.4, 140/927, 92.94, 102; 267/91, 99, 101; 5/269 51 Aug. 22, 1972 [56] References Cited UNITED STATES PATENTS 2,111,026 3/1938 Lewis 140/3 1,788,868 1/1931 Hanauer ..5/269 3,380,484 4/ 1 968 Kraszeski 140/3 3,033,243 5/1962 Cornish ..140/102 Primary ExaminerLowell A. Larson Att0rneyScrivener, Parker, Scrivener and Clarke S 7 ABSTRACT In the manufacture of spring interiors for mattresses, seats and the like a plurality of springs are linked together by helical wires which are rotated and advanced much in the manner of screws. ln order to prevent the helical wires becoming unlinked stops are formed by distorting the helical wires at positions spaced from their ends. Each stop preferably comprises a closed loop, and this preferably embraces a wire of an adjacent spring.

9 Claims, 5 Drawing Figures PATENTED AUG 2 2 I972 SHEET 2 OF 2 g, A J J SPRING INTERIORS FOR MA'ITRESSES, SEATS AND THE LIKE This invention relates to spring interiors for mattresses, divans seats (that is both seats proper and seat backs) and the like, and in particular to spring interiors of the kind (hereinafter referred to as the kind specified) comprising a plurality of springs linked together by helical wires. The springs linked by the helical wires may be individually formed springs or they may comprise coiled spring wires integrally connected to adjacent coils; springs of the kind, linked by helical wires, being, for example, described and illustrated in British Pat. No. 1,095,980 of Multilastic Limited. Throughout this specification there are numerous references to helical wires being linked to springs, and it is to be understood that these references extend, where the contexts permit, to helical wires linked to wires attached to or constituting integral extensions of the springs proper.

In the assembly of spring interiors of the kind specified it is the normal practice to locate the springs to be linked in the desired relative positions and to link them with a helical wire by rotating the helical wire and causing it to advance much in the manner of a screw. Successive helical wires are added in the same manner. It will be appreciated that because a helical wire can be so readily linked to the springs by simple rotation accompanied by longitudinal movement, the helical wire can just as easily be unlinked from the springs by a continuation or a reversal of these movements. It is found that unless special precautions are taken, helical wires tend to become gradually unlinked when the spring interior is in use. If a helical wire becomes unlinked or partially unlinked in this way there is not only the danger that the previously linked springs will become detached from one another but also the danger that the end of the helical wire will project from the side of the spring interior. If this occurs when the spring interior forms part of a mattress, for example, the projecting end of the helical wire may scratch someone or tear bedclothes or garments. It is therefore of great importance to prevent the helical wires from becoming unlinked from the springs. To this end it has hitherto been the practice to deform the last turn at each end of each helical wire so that it forms a closed loop, this loop embracing a wire forming part of one of the springs linked by the helical wire, or embracing some other adjacent part of the spring interior. This practice is only satisfactory when the loops are properly formed so that the wires or other parts which they embrace cannot escape. However, it is found to be difficult in normal manufacture to ensure the correct fonnation of all the loops due to the large number of loops in each spring interior, the resilience of the helical wires and the need high degree of accuracy required. The aim of the present invention is to provide a more reliable method of preventing a helical wire from becoming unlinked from a spring interior.

From one aspect the present invention comprises a method of making a spring interior of the kind specified in which the helical wires are linked to the springs by being rotated and advanced in the manner of screws, the method being characterized in that at least one of the helical wires, after it has been linked to the springs, is permanently deformed at a position spaced from the ends of the helical wire, to produce a stop capable of preventing the helical wire from being unlinked from the springs.

The stop is such that if there is present no other means for preventing the helical wire from being unlinked the stop alone would prevent such unlinking. The stop may form a discontinuity in the helix such that the helical wire can no longer be rotated and moved longitudinally in the manner of a screw. For example if the stop comprises a closed loop it is normally impossible for screwlike movement of the helical wire to occur more than a few turns at the most. In a preferred method the stop comprises a closed loop which is itself linked to a spring or springs of the spring interior. With this arrangement rotation of the helical wire through more than a small part of a single turn is usually prevented.

It is to be understood, however, that additional means may be provided with a view to preventing the helical wires becoming unlinked; in particular as it normally remains necessary to turn in the end portions of the helical wires to render the sharp ends inaccessible, it may be desirable to continue to form loops at the ends of the helical wires. Nevertheless, the loops need no longer be formed with such great accuracy as before, and need no longer be fully closed.

In a preferred method the stop is formed by the rotation of a small part of the helical wire about an axis, or adjacent axes, transverse to the axis of the helical wire. The part is preferably rotated through an angle of about about an axis which is substantially at right angles to and which intersects or passes close to the axis of the helix. The rotation of the small part if preferably in the sense such that in the initail stages of rotation the small part of the helical wire becomes more steeply inclined to the axis of the helix than it was initially.

From another aspect the present invention consists in a spring interior which has been made by the method outlined above.

From another aspect the present invention consists in a spring interior of the kind specified in which at least one of the helical wires is so shaped at a position spaced from the ends thereof as to present a stop which is capable of preventing the helical wire from being unlinked from the spring.

From yet another aspect the present invention consists in apparatus for carrying out the method outlined above, which apparatus comprises locating means for locating portions of the springs, and means for causing a helical wire to be advanced and rotated in the manner of a screw to link said parts of the springs together, the apparatus being characterized by the provision of a twisting head in an intermediate part of the path of a helical wire, the head having a transverse groove which receives a short part of the helical wire and being rotatable about an axis transverse to that of the helical wire so as to form the stop.

One particular form of apparatus embodying the present invention is intended for use in conjunction with the apparatus which is described and illustrated in British Pat. No. 1,095,980 referred to above. That apparatus is adapted to make spring units or spring interiors from bands of springs and includes a linking station where there are pairs of jaws arranged side-by-side in a row. One jaw of each pair is fixed, while the other is pivoted so that it can move between an open position and a closed position. The movable jaws have a common pivot axis which extends lengthwise of the row. Each jaw is formed with a semi-cylindrical channel parallel with the pivot axis, the channels in each pair of jaws together forming a tubular opening when the jaws are closed, all the openings being axially aligned. The channels in the jaws are themselves grooved with parthelical grooves such that when each pair of jaws is closed the grooves therein form a continuous helix around the tubular opening. When the apparatus is in use the jaws are opened, two wires constituting extensions of adjacent springs are disposed between each pair of jaws and the jaws are then closed. There is a gap between each pair of jaws and the next to allow the wires leading to the spring extensions in the jaws to project laterally from the row of jaws. A helical wire is then screwed along the helical grooves defined by the jaws, and is thus linked to the spring extensions in the jaws. The helical wire is trimmed to length, and the trimmed ends are deformed to form closed loops which embrace appropriate adjacent wires of the springs. As described above, however, unless special care is taken the loops may not always be perfectly formed. Finally the jaws are opened and the helical wire, with the parts linked to it, is moved away from the fixed jaw past the movable aw.

The novel part of the apparatus which embodies the present invention operates in the gap between two adjacent fixed jaws. These jaws may be at or near the center of the row, or they may be towards one end of the row. The latter position is to be preferred when the jaws are of the kind which are individually removable and replaceable to enable spring units of different widths to be made, for the novel part of the apparatus can then remain fixed while jaws elsewhere in the row are removed or replaced.

The novel features of the present invention are illustrated in the accompanying drawings, in which:

FIG. 1 shows part of a helical wire which has just been linked to the springs (not shown) of a spring interior, and a twisting head and associated parts sectioned along the line 11 of FIG. 2;

FIG. 2 is a section along the line 2-2 of FIG. 1;

FIG. 3 is a view of the helical wire and as twisting head seen from the left of FIG. 1;

FIG. 4 is a view of the helical wire similar to that shown in FIG. 3 but after the stop has been formed; and

FIG. 5 is a plan view of part of a spring interior embodying the invention.

The novel part of the apparatus is shown inFIGS. l to 3 and comprises a shaft I mounted in fixed bearings 2 for rotation about an axis at right angles to the axis of the helical wire 3 and intersecting that axis. One end of the shaft 1 terminates closely adjacent to the helix axis and constitutes a twisting head 4. The head has a transverse groove 5. The other end of the shaft 1 is provided with a pinion 6 which engages a rack 7 slidable in a direction parallel to the row of jaws (not shown). The rack 7 is moved to and fro by a double-acting pneumatic piston-and-cylinder unit (not shown), and the arrangement is such that on each transverse of the piston the shaft 1 rotates 180. The rack 7 and pinion 6 and the piston-and-cylinder unit are so located as not to interfere with the passage to the linking station of the springs to be linked. To this end the shaft 1 points substantially in the direction of movement of the spring interior following the linking of a helical wire.

The arrangement is such that when the helical wire 3 is introduced into the closed jaws the groove 5 is inclined to the helix angle and is so positioned that the helical wire extends into the groove without being deformed. When the ends of the helical wire are trimmed and the trimmed ends fonned into loops the piston-and-cylinder unit operates to rotate the twisting head 4 through in a sense such that during the initial stages of rotation the groove, and the short part 8 of the helical wire 3 which extends through the groove becomes more steeply inclined to the helix axis than it was initially. The sense of rotation of the head 4 is indicated by the arrow 9 in FIG. 3. When the jaws are subsequently opened and the helical wire 3 moves away from them that part 8 of helical wire which was in the groove 5 passes from the end of the groove without hindrance. The head 4 is returned to its initail position at some later stage in the cycle, before the next helical wire is introduced into the closed jaws.

Due to the resilient nature of the helical wire 3 there may be a slight return movement of the deformed portion of the wire, but the arrangement is such that in the final state the helical wire is formed with a non-planar loop 10 (as shown in FIG. 4) which is closed at two points 11 where constituent wires tough each other. The actual shape of the loop depends on a number of factors such as the pitch and diameter of the helical wire its thickness and its resilience. Further, the shape depends on the number of turns of the helical wire between the adjacent jaws and thus free to bend when the stop is formed. In preferred methods there are between two and four turns of the helical wire unsupported and from which the stop is formed.

FIG. 5 shows part of a spring interior made by the apparatus. There are a plurality of bands of springs disposed side-by-side, sections of two whole ones and part of a third are shown. Each band is formed from a single length of spring wire bent to form compression springs 12 of substantially helical shape, integrally interconnected by straight extensions 13 running lengthwise of the band. The end portions 14 of the springs 12 are linked by transverse helical wires 15. The ends of the helical wires are trimmed and formed into loops 16 which may or may not be closed. Each helical wire 15 is formed with a stop 17 similar to that shown in FIG. 4, the stop being spaced from the ends of helical wire. It will be understood that if any of the loops 16 is not linked to an adjacent spring, or becomes unlinked from such a spring, the helical wire of which it constitutes the end portion may be rotated through a small angle but that the engagement between the stop 17 on that helical wire and the springs adjacent to it will prevent any significant axial movement of the helical wire.

In order to simplify the illustration as much as possible the stops 17 are shown as not being linked to the adjacent springs. In a preferred arrangement, however, the stops 17 are linked to the adjacent springs. Preferably the stops are linked to those parts such as 18 where the springs are turned from lying inside the helices and are directed transversely to them.

shield the relatively sharp trimmed ends of the helical wires.

I claim:

1. A method of making a spring interior of the kind comprising a plurality of compression spring elements linked together by helical wires, and in which the helical wires are linked to the spring elements by being rotated and advanced in the manner of screws, the method being characterized in that at least one of the helical wires, after it has been linked to the spring elements, is permanently deformed by rotation of a small part of the helical wire, spaced from the ends of the helical wire, about at least one axis transverse to the axis of the helical wire to produce a stop capable of preventing the helical wire from being unlinked from the spring elements.

2. A method according to claim 1 in which the deformation is such that the stop comprises a closed loop.

3. A method according to claim 2 in which the closed loop is linked to at least one spring element of the spring interior.

4. A method according to claim 1 in which the rotation is in a sense such that in its initial stages said small part of the helical wire becomes more steeply inclined to the axis of the helix than it was initially.

5. A spring interior of the kind comprising a plurality of compression spring elements linked together by helical wires, and in which at least one of the helical wires is shaped at a position spaced from the ends of the helical wire as to present a stop which is capable of preventing the helical wire from being unlinked from the spring elements, characterized in that the stop includes a small part of the helical wire twisted about at least one axis transverse to the axis of the helical wire.

6. A spring interior according to claim 5 in which the stop comprises a closed loop.

7. A spring interior according to claim 6 in which the closed loop is linked to at least one spring element of the spring interior.

8. Apparatus for use in making a spring interior of the kind comprising a plurality of compression spring elements linked together by helical wires, which apparatus is of the kind comprising locating means operative to locate portions of said spring elements, and insertion means operative to cause a helical wire to be advanced and rotated in the manner of a screw along a predetermined path so as to link said portions of the spring elements together, the apparatus being characterized in that it includes a twisting head disposed in an intermediate part of said path, said twisting head having a transverse groove through which said path extends, and rotating means operative to rotate said twisting head about an axis transverse to that of said path where it extends through said groove, whereby when a helical wire lies in said path, linking said portions of the spring elements together, and a part thereof extends through said groove, rotation of said twisting head by said rotating means causes deformation of said helical wire to produce a stop capable of preventing said helical wire from being unlinked from said spring elements.

9. Apparatus according to claim 8 in which said rotating means is operative to rotate said twisting head through about 

1. A method of making a spring interior of the kind comprising a plurality of compression spring elements linked together by helical wires, and in which the helical wires are linked to the spring elements by being rotated and advanced in the manner of screws, the method being characterized in that at least one of the helical wires, after it has been linked to the spring elements, is permanently deformed by rotation of a small part of the helical wire, spaced from the ends of the helical wire, about at least one axis transverse to the axis of the helical wire to produce a stop capable of preventing the helical wire from being unlinked from the spring elements.
 2. A method according to claim 1 in which the deformation is such that the stop comprises a closed loop.
 3. A method according to claim 2 in which the closed loop is linked to at least one spring element of the spring interior.
 4. A method according to claim 1 in which the rotation is in a sense such that in its initial stages said small part of the helical wire becomes more steeply inclined to the axis of the helix than it was initially.
 5. A spring interior of the kind comprising a plurality of compression spring elements linked together by helical wires, and in which at least one of the helical wires is shaped at a position spaced from the ends of the helical wire as to present a stop which is capable of preventing the helical wire from being unlinked from the spring elements, characterized in that the stop includes a small part of the helical wire twisted about at least one axis transverse to the axis of the helical wire.
 6. A spring interior according to claim 5 in which the stop comprises a closed loop.
 7. A spring interior according to claim 6 in which the closed loop is linked to at least one spring element of the spring interior.
 8. Apparatus for use in making a spring interior of the kind comprising a plurality of compression spring elements linked together by helical wires, which apparatus is of the kind comprising locating means operative to locate portions of said spring elements, and insertion means operative to cause a helical wire to be advanced and rotated in the manner of a screw along a predetermined path so as to link said portions of the spring elements together, the apparatus being characterized in that it includes a twisting head disposed in an intermediate part of said path, said twisting head having a transverse groove through which said path extends, and rotating means operative to rotate said twisting head about an axis transverse to that of said path where it extends through said groove, whereby when a helical wire lies in said path, linking said portions of the spring elements together, and a part thereof extends through said groove, rotation of said twisting head by said rotating means causes deformation of said helical wire to produce a stop capable of preventing said helical wire from being unlinked from said spring elements.
 9. Apparatus according to claim 8 in which said rotating means is operative to rotate said twisting head through about 180* . 